This study will explore whether the beneficial effect of prostacyclin seen in patients with pph can be extended to patients with pulmonary hypertension secondary to the scleroderma spectrum of diseases. Because endothelial dysfunction may play a role in the pathogenesis of the scleroderma spectrum of diseases, resulting in vasospastic manifestations such as raynaud's phenomenon, there is a reasonable possibility that prostacyclin will provide benefits beyond its potential effects on pulmonary hypertension. Indices of such potential secondary benefits will be tracked in the study.